Not just it they exist:
The delineation of OSHA and the U.S. Coast Guard authority over inspected vessels has been unchanged since the signing of a Memorandum of Understanding (reference C.2.) in 1983. The Coast Guard has statutory authority to prescribe and enforce regulations affecting the safety and health of seamen on board vessels inspected and certificated by the agency, and has issued comprehensive standards for working conditions on inspected vessels. Therefore, OSHA may not enforce the OSH Act with respect to “seamen” on inspected vessels including the master, ship’s officers and crew members.
The extent of the Coast Guard preemption of OSHA authority over commercial uninspected fishing vessels underwent significant changes in 1991. In response to Public Law 100-424 (reference C.3.), the U.S. Coast Guard developed and issued specific regulations (reference C.4.) for commercial uninspected fishing, fish processing, and fish tender vessels to improve the overall safety and health working conditions of commercial fishing industry vessels .
OSHA authority over commercial uninspected vessels (other than uninspected fishing vessels) remains unchanged. The U.S. Coast Guard has published applicable regulations for uninspected vessels (See reference C.5.).
https://www.osha.gov/enforcement/directives/cpl-02-01-020